‘Climate security’ conventionally refers to climate change being a multiplier of threats to national security, international peace and stability, or human security. Here we identify a hitherto overlooked inverted climate security discourse in which climate responses (rather than climate impacts) are held to pose an existential threat to dominant fossil fuel-dependent ‘ways of life’, justifying extraordinary measures—societal climate security. In doing so, we seek to make three novel contributions. First, we set out how societal securitization applies beyond a national frame and in relation to transnational threats like climate change, arguing it promotes not just exceptional measures but also palliative ones that avoid challenging incumbent identities. Second, we draw on recent evidence and extant literatures to show that 'societal climate security' already has substantial material emanations in the form of exceptional measures, deployed domestically against climate protestors and externally against climate migrants, in the name of societal order and cohesion. Third, we turn to wider climate policy implications, arguing that societal securitization tilts policy agendas further away from rapid mitigation pathways and toward promissory measures such as ‘geoengineering’—schemes for future, large-scale technological interventions in the climate system—that may appear less threatening to established societal identities. While there are sound ecological and humanitarian rationales to research such technologies, in the context of societal securitization these can be appropriated to defend dominant ‘ways of life’ instead. To conclude, we reflect on how, were it attempted, deployment of solar geoengineering for societal security would affect security politics more widely.